Medications are often delivered to patients in the form of inhaled aerosols—gaseous suspensions of very fine liquid or solid particles in which medications are entrained. So-called pulmonary delivery of medication is in many instances a very efficient manner of delivering biological and chemical substances to the patient's bloodstream. Pulmonary delivery is especially efficient when the medication is delivered with a digitally controlled device such as a “metered dose inhaler” (“MDI”) or other type of inhaler that incorporates ejector heads that are suitable for creating aerosols having very small droplet size. Such inhalers are often used to deliver asthma medications directly into a patient's lungs where the medications are rapidly absorbed into the blood stream.
As with any device intended to deliver medication to a patient, it is essential that an inhaler is maintained in proper operating condition to ensure, among other things, that the proper dosage of medication is administered to the patient, and that the device is suitably clean. However, the ejector heads that are used in digital inhalers such as MDIs can become clogged over time and repeated use. Moreover, some types of medications can accumulate on the surfaces of the ejector head. In both cases, whether one or more nozzles becomes clogged or the nozzle orifice size is reduced due to accumulated residue, the dosage of medication delivered to the patient may be affected, resulting in a lower dosage than might be needed. Clogging and accumulated residue may also impact the cleanliness of the inhaler.
There is an ongoing need to provide inhalers with smaller and very precisely controlled drop sizes. As these requirements increase, there is an ongoing need to provide such inhalers and other medication delivery apparatus having improved reliability.